Abstract

Why do portfolio managers actively manage their stock portfolios? The finance literature suggests the importance of financial incentives, effort, information and career concerns. We suggest that personality can also be a factor. We perform an experiment with industry experts. The experiment documents that, in a group decision setting, subjects with high aggression, measured by a standard psychology test, were much more likely to deviate from market tracking. In an individual decision setting, these same subject’s behavior was not significantly affected by aggressiveness. This result suggests that, in group settings, personality, rather than cognitive biases, might be the most important source of behavioral deviations from the rational choice paradigm.